JP2007332950A - Fuel injection device for internal combustion engine and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device and its manufacturing method for restraining cost. <P>SOLUTION: This fuel injection device is composed of a hollow body for storing a throttle valve for injection, and the valve has a calibration pipe for discharging fuel from a control chamber. The calibration pipe is normally closed and held by a shutter controlled by an electromagnet composed of a magnetic core and an electric coil stored in an annular slot of the core. The coil has a cylindrical outside surface, and the outside surface forms a clearance surrounded by the fuel sent out of the calibration pipe together with the annular slot. The coil is particularly composed of a bobbin having a pair of branch parts for supporting a pair of plugs for supplying electricity of the coil. The plugs are included in a block of at least a partially nonmagnetic material. The bobbin has a substantially cylindrical rib and flanges parallel in two planes. One of the flanges is adjacent to an end part of the plugs, and the other has a small diameter for forming a flow passage for the fuel between the calibration pipe and the clearance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection device for an internal combustion engine and a method for manufacturing the same.

  In particular, the present invention relates to an injection device comprising a hollow body that contains a throttle valve for injection therein, said valve having a calibration line for discharging fuel from the control chamber. Typically, the conduit is kept closed by a shutter controlled by an electromagnet comprising a magnetic core and an electrical coil housed in an annular slot of the core.

  Usually, the electromagnet presses the core against the fixed shoulder of the hollow body, for example, by means of a suitable fixing device such as a ring nut screwed to the hollow body, through the block made of non-magnetic material. Fixed to. The electric coil is formed by a series of rotating parts that are electrically connected to two supply plugs. The rotating part is wound on a support bobbin provided with two equal flanges having equal inner and outer diameters and identical to the inner and outer diameters of the annular slot.

  2. Description of the Related Art An injection device is known in which a bobbin of a coil supports a pair of hollow branch portions, and two plugs fixed to the coil by, for example, a nonmagnetic material block or disk are inserted into the hollow branch portions. This block is relatively expensive to manufacture in terms of mechanical manufacturing and assembly.

  In known injection devices in which the two plugs are parallel to the core axis, it has been proposed to include both a part of the core and a part of the plug in a block made of non-magnetic plastic material, so that this The insert is configured in injection molding. In such an injection device, the bobbin has an outer diameter that defines a flow path for the plastic material in the annular slot of the core and completely covers the coil during injection molding. Such injectors exhibit the disadvantage of preventing the dissipation of heat generated from the coil after electromagnet excitation. In fact, the coil is completely coated with a plastic material that substantially reduces the heat exchange capacity of the coil with the surroundings, in particular, it transfers heat generated to diesel fuel that flows through the magnetic core and is later discharged. To reduce the capacity.

  An object of the present invention is to provide a fuel injection device that suppresses costs and eliminates the drawbacks of prior art electromagnetic injection devices and a method for manufacturing the same.

  The object of the present invention can be achieved by the fuel injection device according to claim 1 and the method for manufacturing the injection device according to claim 13.

  Several preferred exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

  In FIG. 1, a fuel injection device for an internal combustion engine is indicated generally by 1, which comprises a casing formed by a tubular hollow body 2 having a shaft 3. The hollow body 2 comprises two tubular stretches 4 and 6, whose inner diameter decreases from the free end and is rounded by an inner shoulder 7 orthogonal to the axis 3. The tubular stretch 6 houses a throttle valve 8 for injection, which is sealed against the shoulder 10 of the tubular stretch 6 via a ring nut 9.

  The throttle valve 8 includes a control chamber 11 having a calibration line 12 that discharges fuel under pressure from the control chamber 11. Normally, the calibration line 12 is held closed by a shutter 13, which is pressed against the contrast surface 14 by a helical compression spring 16 which will be described in detail later. The calibration line 12 is opened by an antagonistic action added by an actuator formed by an electromagnet 17 acting on a disk-type armature 18 fixed to the shutter 13. The electromagnet 17 and the armature 18 are accommodated in the tubular stretch 4 of the hollow body 2.

  The electromagnet 17 includes an annular magnetic core 19 having an axial through slot 21 in which a spring 16 is housed. The core 19 includes a cylindrical portion 20 and a flange 22, and the flange is supported on the shoulder portion 7 via a spacer ring 23. In addition, the core 19 has an annular slot 24 designed to accommodate the electrical coil 26. The annular slot 24 (FIG. 3) has a cylindrical inner surface 25 and a cylindrical outer surface 30.

  The coil 26 is formed by a series of rotating parts 27 wound around a bobbin 28 (see FIG. 2) made of an insulating plastic material and having a C-shaped cross section. In particular, the bobbin 28 is formed by a cylindrical rib 29 whose inner diameter is substantially the same as the diameter of the cylindrical inner surface 25 of the slot 24 and two planar flanges 31 and 32. The rotating portion 27 is installed so as to define an outer surface 33 of the substantially cylindrical coil 26.

  The electromagnet 17 further includes two plugs 34 parallel to the axis 3 and laterally spaced from each other for supplying electricity to the coil 26. Each plug 34 has a first end 36 that is electrically connected to a corresponding terminal of the coil 26 in a known manner. Each plug 34 further includes a central portion 37 and a second end 38 that protrudes beyond the tubular stretch 4 (FIG. 1) of the hollow body 2 in use. The first end portion 36 is inserted into a corresponding branch portion 39 (FIGS. 2 and 3) formed like a bearing cylinder, and the branch portion is formed as a single piece with the flange 32 of the bobbin 28. Preferably, the two branch portions 39 are opposed to each other in the radial direction, and each of them is inserted into a corresponding through hole 41 formed in the annular slot 24 of the core 19.

  The electromagnet 17 further includes a single block 42 made of a nonmagnetic plastic material, and the tubular portion 20 of the core 19 and the intermediate portion 37 of the plug 34 are embedded therein. Preferably, the non-magnetic material may be polyamide reinforced glass fibers such as “Zytel” or “Stanyl”. In particular, the block 42 includes a tubular portion 20 of the core 19 and has a first portion 43 supported on the flange 22 of the core 19. The portion 43 has an outer diameter that approximates the inner diameter of the tubular stretch 4 (see FIG. 1), and is thus connected via a gas seal 44.

  The block 42 includes a second portion 46 having an outer diameter smaller than that of the first portion, and is rounded by an annular shoulder 47 orthogonal to the shaft 3. The portion 46 protrudes outside the tubular stretch 4 and the shoulder 47 is spaced from the upper edge 48 of the stretch 4 by a predetermined distance. The portion 46 has two blind shaft spaces 49, each of which is provided at a position corresponding to the corresponding portion 38 of the plug 34. The block 42 further includes a through central slot 50 that, together with the slot 21 in the core, forms a discharge line for fuel delivered from the calibration line 12. The slot 50 houses a portion of the spring 16 and has a shoulder 55 on which the spring 16 itself is supported.

  The shoulder 47 of the block 42 advantageously defines a mounting surface for a Belleville spring or wave washer compression spring 51, which is against the shoulder 47 by a ring nut 52 in the form of an inverted hook. Pressed. In particular, the ring nut 52 has a side wall 53 having an inner thread screwed to the outer thread of the tubular stretch 4. The ring nut 52 further includes an annular end wall 54 that opens radial play and surrounds the portion 46 of the block 42 and is in use at the upper edge 48 of the tubular stretch 4. The annular wall 54 defines an axial contrast surface with respect to the spring 51.

  The end 38 of each plug 34 is designed to be electrically coupled to a respective terminal 56. The two terminals 56 are supported by two corresponding terminal blocks 57 housed in an electrically insulating cap or lid 58. In use, the end 38 of each plug 34 protrudes from the corresponding blind shaft space 49 of the block 42 and a gas seal 59 fits around this end 38. Two terminal blocks 57 are fitted onto the end portion 38 of the plug 34, and the lid 58 is fitted to the tubular stretch 4 of the hollow body 2.

  According to the present invention, the coil 26 is formed such that its outer surface 33 is surrounded by fuel delivered from the calibration line 12. In particular, the outer surface 33 of the coil 26 forms a gap 61 through which fuel flows with the outer surface 30 of the annular slot 24.

  1-4, each of the holes 41 in the core 19 has a diameter that is larger than the diameter of the outer surface of the corresponding branch 39, so that another gap 62 is formed. During the injection of the plastic material to form the block 42, each gap 62 is integrally formed with a bearing cylinder 60 including a corresponding branch portion 39. However, since such a nonmagnetic material does not penetrate the gap 61, the surface 33 of the coil 26 remains exposed. In particular, according to the variant of FIGS. 1 to 3, the flange 32 of the bobbin 28 advantageously surrounds the surface 33 of the coil 26 because its outer diameter is advantageously smaller than the outer diameter of the outer surface 30 of the annular slot 24. An annular channel 63 for fuel is formed.

  In the variation shown in FIG. 4, the diameter of the flange 32 ′ of the bobbin 28 is substantially the same as the diameter of the upper flange 31 and the outer surface 30 of the annular slot 24. However, the flange 32 'is provided with at least two recesses 64 (a series of recesses in FIG. 7) that form a number of flow paths 66 for the fuel surrounding the surface 33 of the coil 26.

  According to the embodiment of FIGS. 5 and 6, the diameter of the hole 41 in the core 19 is substantially the same as the outer diameter of the branch part 39 of the bobbin 28, and the branch part 39 is pressure fitted into the hole 41. . The non-magnetic material of the block 42 now surrounds only the portion 67 of the branch point 39 protruding from the core 19. In the variant of FIG. 5, the flange 32 of the bobbin 28 has a diameter that is smaller than the diameter of the annular outer surface 30, thus forming an annular passage 63 for the fuel as in FIG. In the variation of the embodiment of FIG. 5 shown in FIGS. 6 and 7, the flange 32 'has a series of recesses 64, forming a series of channels 66 as in FIG.

  The injection device 1 includes the non-magnetic material of the block 42 therein, the core 19 and the core 19 and The coil 26 can be manufactured using a manufacturing method that involves injecting into an existing mold. This manufacturing method includes the following steps.

Providing a bobbin 28 for a coil 26 having a C-shaped cross section, the bobbin having two branches 39 each designed to receive a first end 36 of a corresponding plug 34;
-Rotating the rotating part 27 of the coil 26 on the bobbin 28 and inserting the corresponding first end 36 of the plug 34 into each branching part 39;
Inserting the bobbin 28 into the core 19 together with the coil 26 and the plug 34;
Providing a mold for forming a block 42 made of a non-magnetic material for containing at least a part of the core 19, at least a part of the branch part 39 of the bobbin 28 and at least a part of the plug 34;
A step of providing the core 19 together with the bobbin 28 and the plug 34 in a mold;
-Providing the core to the mold so as to form a gap 61 between the outer surface 33 of the coil 26 and the annular slot 24 of the core 19;
Injecting a nonmagnetic plastic material into the mold, and separating the block of nonmagnetic material thus formed from the core and mold.

  Further, the following process is performed.

-Connecting the compression spring 51 to the block 42;
A step of inserting the connected block 42 into the tubular stretch 4 of the hollow body 2 of the injection device 1, and a step of locking the block 42 in the tubular stretch 4 with a ring nut 52 via a compression spring 51.

  From the above, the advantages of the injection device 1 of the present invention and the corresponding manufacturing method are clear when compared with the prior art. In particular, the fuel delivered from the calibration line 12 always surrounds the outer surface 33 of the coil 26, so that heat generated by the passage of current in the rotating part 27 is quickly dissipated, and the life of the injection device 1 is increased. To do. Furthermore, the manufacturing method of the present invention makes it possible to easily obtain the fuel flow paths 63 and 66 to the gap 61 between the coil 26 and the annular slot 24 and to assemble various components of the injection device 1. Enables simplification.

  It should be understood that various modifications and changes can be made to the above-described fuel injection device and method for manufacturing the same without departing from the scope of the claims. For example, the block 42 of non-magnetic material can be differently shaped, or two or more that can block the plug 34 to the core 19 and the core to the tubular stretch 4 of the hollow body 2. It is possible to replace it with other parts.

It is a fragmentary sectional view of the radial direction of the fuel injection device by a 1st embodiment of the present invention. It is a perspective view which shows the partial cut part of the detail of FIG. FIG. 2 is an enlarged cross-sectional view of FIG. 1 with some parts omitted. 3 is a portion of FIG. 3 according to a variation of the embodiment of FIG. FIG. 4 is a detail of FIG. 3 according to another embodiment of the injection device. It is a modification of embodiment of FIG. FIG. 7 is a cross-sectional view of the detail of FIG. 2 taken along line VII-VII of FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus 2 Hollow main body 3 Axis 4, 6 Tubular stretch 8 Throttle valve 11 Control chamber 12 Calibration pipe line 13 Shutter 17 Electromagnet 19 Core 21, 50 Slot 24 Annular slot 26 Coil 28 Bobbin 29 Rib 31, 32, 31 ', 32 'flange 34 plug 39 branching part 42 block 51 compression spring 52 ring nut 61 gap

Claims (14)

A fuel injection device (1) for an internal combustion engine comprising:
Comprising a hollow body (2) in which an injection throttle valve (8) is housed, said valve having a calibration line (12) for the discharge of fuel from the control chamber (11);
The shutter (13) in which the calibration line (12) is controlled by an electromagnet (17) comprising a magnetic core (19) and an electric coil (26) housed in an annular slot (24) of the core (19). ) Is normally kept closed,
The fuel injection device according to claim 1, wherein the coil (26) is formed so as to be surrounded by fuel delivered from the control chamber. The coil (26) has an outer surface (33), the outer surface (33) is substantially cylindrical and forms a gap (61) with the annular slot (24) so as to be surrounded by the spilled fuel. The injection device according to claim 1. The plug (26) is included in a pair of branch portions (39) supporting the pair of plugs (34) for supplying electricity, the core (19), and a block (42) of nonmagnetic material. 34. The injection device according to claim 2, comprising a bobbin (28) having at least a part (37) of 34). The bobbin (28) has a substantially cylindrical rib (29) and two flanges (31, 32; 31, 32 ') that are substantially planar and parallel to each other to form a C-shaped cross section; The branch (39) is supported by one of the flanges (31, 32; 31, 32 ′), and the block (42) includes at least a part (67) of the branch (39). The injection device according to claim 3. Flange (31) supporting the branch (39) so that the other (32) of the flanges (31, 32) forms an annular flow path (63) for the fuel flowing in the gap (61). The injection device according to claim 4, wherein the injection device has a smaller diameter than the above. The other (32 ′) of the flanges (31, 32 ′) has at least two peripheral recesses (64) so as to form a corresponding flow path (66) for the fuel flowing into the gap (61). The injection device according to claim 4. The core (19) and the block (42) are formed with corresponding central slots (21, 50) communicating with the gap (61), and the fuel delivered from the calibration line (12) 7. An injection device according to claim 5 or 6, characterized in that is discharged through the central slot. The branch portion (39) is designed to be inserted into two holes (41) opposed in the radial direction of the core (19), and the block (42) projects from the hole (41). 8. An injection device according to claim 7, comprising at least a part (67) of (39). The block (42) is co-molded with the core (19) so that the hole (41) forms a corresponding gap (62) with the branch (39) and fills the corresponding gap (62). The injection device according to claim 8, wherein Each of the branch portions (39) has an outer surface attached to the surface of the corresponding hole (41), so that the block (42) includes only the part (67) of the branch portion (39). The injection device according to claim 8. The block (42) is composed of two parallel cylindrical spaces (49), each provided at a position corresponding to the second end (38) of the corresponding plug (34). Is provided with a respective sealing portion (44) provided between the second end portion (38) and the corresponding parallel space (49) of the block (42). The injection device according to claim 9 or 10. The block (42) is connected to the hollow body (2) by a ring nut (52) screwed to the hollow body (2), and a compression spring (51) is connected to the ring nut (52) and the hollow body ( The injection device according to any one of claims 3 to 11, wherein the injection device is provided between (2) and (2). It comprises a hollow body (2) in which an electromagnet (17) for controlling an injection throttle valve (8) is housed. The electromagnet (17) comprises a magnetic core (19), an electric coil (26) and the coil ( 26) consisting of two plugs (34) electrically connected to the core (19) in which the core (19) accommodates the coil (26) and two channels for the flow path of the plug (34). A method of manufacturing a fuel injection device (1) for an internal combustion engine having a hole (41), said method comprising the following steps:
A step of providing a bobbin (28) for a coil (26) having a C-shaped cross section, wherein the bobbin (28) accommodates a first end (36) of a plug (34) each corresponding thereto. Provided with two branches (39) designed to
Rotating the coil (26) on the bobbin (28) and inserting the first end (36) of the corresponding plug (34) into each branch (39);
Inserting the bobbin (28) into the core (19) together with the coil (26) and the plug (34);
A block (42) of non-magnetic material to encompass at least a portion of the core (19), at least a portion of the branch (39) of the bobbin (28) and at least a portion of the plug (34); Providing a mold to be formed,
Providing the core (19) together with the bobbin (28) and the plug (34) in a mold;
Providing a core to the mold so as to form a gap (61) between an outer surface (33) of the coil (26) and the annular slot (24);
A method for manufacturing a fuel injection device, comprising the steps of injecting a non-magnetic plastic material into the mold and separating the block (42) thus formed from the core and the mold. Connecting a compression spring (51) to the block (42);
Inserting the connected block (42) into the tubular stretch (4) of the hollow body (2), and connecting the block (42) and compression spring (51) in the tubular stretch (4) to a ring nut ( A method according to claim 13, characterized in that it comprises the step of locking according to 52).

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